Plane misses approach at airport due to fog

Melbourne's morning pea-soup fog is so thick a pilot had to pull out of their descent on a flight into Melbourne Airport.

A Virgin Australia flight from Canberra was heading into Melbourne Airport when the pilot decided the fog was too heavy to land. They were forced to pull the Boeing 737 out of the landing. The flight was then diverted to Sydney.

A Virgin Australia spokeswoman said the "missed approach" was routine and did not pose a risk to customers.

Several flights across numerous airlines have also been delayed by up to an hour, and one Qantas flight had to be diverted, an airport spokeswoman said. Flights continue to arrive and depart at the airport.

The fog is thick across Melbourne, with many social media users posting snaps of obscured landmarks.

The Bureau of Meteorology is forecasting the morning fog will clear by midday, with an expected top of 15 and a sunny afternoon.

Wednesday morning's foggy conditions were caused by cold overnight conditions. That combined with some low-lying moisture in the atmosphere helped generate the thick fog, the Bureau of Meteorology's senior forecaster Tom Delamotte said.

"We're expecting a gradual improvement over the next two to three hours. I imagine it would largely have cleared between 11am and midday. Once that clears it does look like we'll have a bit of sun about, light winds, a fairly pleasant afternoon."